nixon flowmeters industrial type turbine

8/13/2019 Nixon Flowmeters Industrial Type Turbine

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. . . . . . . . P r e c i s i o n C o u n t s

NT

Ind ustri al Type Turbi ne Flow met er

Introduction

The Nixon range of turbine flowmeters offers highaccuracy and high reliability. Over 30 years,thousands of units have been sold to all classes of industry, and the meters have an excellent reputationfor durability.

Many leading flowmeter companies in the U.K. andabroad have the confidence to put their name on ourrange of turbine flowmeters, a sign of the high regardin which the product is held.

The range has been modified and extended over thelast few years to provide a reasonably priced generalpurpose flow transmitter. We now produce the unitsentirely in-house to control quality and availability. The range is available on short deliveries, andpopular sizes are held ex-stock.

Available in a wide variety of body sizes and styles,all NT flowmeters possess an electrical pulse outputdirectly proportional to flowrate, based upon theoperating principle described in this publication.Remote flowrate indication, alarms, totalising andbatch control functions are available utilising our widerange of secondary electronic instruments.

The flowmeters are suitable for use on lubricating ornon-lubricating liquids of low to medium viscosity andare largely insensitive to density variations, pressureor temperature fluctuations.

Contact parts are produced from 316 stainless steel,except rotors which must possess good magneticqualities, and here 431 stainless is used or Ferralium

alloy depending upon the corrosive properties ofthe liquid.

Standard end connections are screwed BSP parallelthread with included 30 degree internal cones toBS5200, but Ermeto threads are also available.Flanged meters are normally to ANSI 150 orBS4504 (DIN) standards, but older type flanges toBS10 tables D-H may also be fitted.

A unique feature of the design is the use of helicallymilled rotors cut from solid in sizes up to 65mm.Bearing bushes are of PTFE/Carbon HY49 or similar,or tungsten carbide depending upon the nature of themetered fluid. In all cases, the spindle is of tungstencarbide with Cobalt binder, and thrust balls of tungsten carbide. Stainless steel ball races are used inthe smaller sizes.

The electrical signal is a sinusoidal pulse of minimumheight 50mV peak at lowest flowrate, rising to 800mVpeak at max flowrate. For normal transmissiondistances pre-amplifiers are not essential since pulseshaping and conditioning are carried out in theappropriate electronic readout unit. In cases whereheavy electrical noise is present or where transmissiondistances are over 500 metres, pre-amplifiers of standard or intrinsically safe design are available ashead mounted weatherproof units and loop powered.

Performance and other details are listed on TechnicalData tables on pages 2 & 3.



NT3 0.5-5 .11-1.1 17000.0 771800.0 ±0.5% 3/ 8“ 1/ 2” ND15

NT5 1.2-10 .22-2.2 5900.0 26780.0 ±0.5% 1/ 2” 1/ 2” ND15

NT7 2-20 .44-4.4 3000.0 13620.0 ±0.5% 1/ 2” 1/ 2” ND15

NT11 5-50 1.1-11 2600.0 11800.0 ±0.5% 1/ 2” 1/ 2” ND15

NT13 8-80 1.8-18 1950.0 8850.0 ±0.5% 3/ 4“ 1/ 2” ND15

NT19 15-150 3.3-33 630.0 2860.0 ±0.5% 1“ 1” ND25

NT24 25-250 5.5-55 350.0 1590.0 ±0.5% 1“ 1” ND25

NT32 45-450 9.9-99 135.0 613.0 ±0.5% 1 1/ 4“ 1 1/ 2” ND40

NT38 65-650 14.5-145 117.0 530.0 ±0.5% 1 1/ 2“ 1 1/ 2” ND40

NT48 110-1100 25-250 67.0 305.0 ±0.5% 2“ 2” ND50

NT65 200-2000 44-440 18.0 82.0 ±0.5% 3“ 2 1/ 2” ND65

NT80 300-3000 66-660 14.0 64.0 ±0.5% - 3” ND80NT100 500-5000 110-1100 7.5 34.0 ±0.3% - 4” ND100

NT150 1000-10000 220-2200 3.4 15.5 ±0.3% - 6” ND150


NT Technical Data

Sizing tabl e

Parts and M ateria l

• Linear Accuracy

• Repeatability

• Response Time

• Output Signal

• Operating Pressure

• Pressure Drop

• Flow Range

• Temperature

• Transmission Distance

• Mounting Altitude

• Maximum Pressure

1 Housing 316 Stainless Steel

2 Bearing Hanger 316 Stainless Steel

3 Rotor 431 Stainless Steel

4 Spindle Tungsten Carbide

5 Bearing Bushes PTFE/Carbon filledor Tungsten Carbide

6 Thrust Ball Tungsten Carbide

7 Pick off coil Stainless Steel body

8 Collar 316 Stainless Steel

9 Circlip 302 Stainless Steel

±0.5% over 10:1 range

±0.1% of reading

50 millisecs for 50% stepchange in flowrate

Sinusoidal pulses50mV - 800mV peakvarying with flowrate

Twice the pressure drop

across the meter plusvapour pressure of liquid

0.2 - 0.5 bar dependingon meter size

10:1 as standard

Wider ranges possible-30°C min150°C max (standard coil)400°C special design120°C intrinsically safe

500 metres max withoutpre-amplifiers for low noiseenvironment

Horizontal or vertical(flow upwards) or inclined

Limited only by end fittings

Flow Range (Linear) Type Number

Ltrs/ Min I.G.P.M. Ltr Imp Gall Linearity

Approx K-Factor Standard End FittingsBSP

ScrewedANSI or

BS10 E FlangeDIN

Flange





NT Operations Prin cipl e

NT3 51 110 25 82

NT5 64 110 25 82

NT7 64 110 25 82

NT11 85 110 38 84

NT13 85 110 38 86

NT19 114 150 51 89

NT24 114 150 51 91

NT32 135 174 64 95

NT38 150 174 64 98

NT48 180 210 76 103

NT65 - 258 100 112

NT80 - 316 100 119

NT100 - 386 167 130

NT150 - 410 167 155

A B C D

A ferritic stainless steel rotor revolves within a non-magnetic housing on the outside of which is located apick off coil containing a permanent magnet. As therotor blades pass the tip of the permanent magnet,the reluctance of the magnetic circuit is changed,and a small a.c. voltage is generated in the coil. The frequency of the a.c. voltage is proportional toflowrate, and the total number of pulses producedrepresents total flow passed through the meter.

The flowmeter may be located some considerabledistance from the associated secondary instrument,and remote flowrate indication, total flow, and remotebatch control are thus possible.

For best results the flowmeter should be installed wellaway from heavy current carrying cables and withcontrol valves etc. located downstream of the meter.

A length of straight pipe of bore equal to the meterinlet should be provided, preferably 10 diameters inlength, and if possible containing flow straighteningvanes at the inlet end. Turbine meters are sensitive toswirl present upstream may cause a change in meterfactor.

Strainers should be provided to minimise the risk of damage due to small solids in suspension. Metersmay be installed in any attitude, but the flow directionand mounting attitude should be advised at the orderstage if other than horizontal.

Varying densities have no appreciable effect on theaccuracy of axial flow turbine meters so far asvolumetric flow is concerned. If readout is required inmass flow terms, we can supply density ortemperature compensation equipment toautomatically correct for density variation. All turbinemeters are to some extent sensitive to viscositychanges and any likely viscosity variation should beadvised at the order stage.

Servicing may be carried out by our service engineersin the field, but meters should be returned to our

factory wherever possible for repair. Bearingreplacement can be effected on site by a skilled fitter,and instructions will be provided on request.

When requesting service visits or spares the full serialnumber should be stated, which immediately gives usaccess to the original order files for the installation.

Allow an extra 50 mm height on dimension 'D' forpick off coil connector.

Instal l at ion a nd u se

Dimensions

Ind ustri al Type Turbi ne Flowm eter




NT Cal ibra t ion m ethod

Water is pumped from storage through the test meter,through a manual control valve into a collecting tankmounted upon a standard weighbridge, the vesselhaving a drain valve for return to storage.

At the commencement of a calibration, water iscirculated through the system and allowed to drainwhilst the operator regulates the control valve to setup the approximate desired flowrate. Next, a smallweight, equal to about 10% of tank capacity is

attached to the weighbridge arm, which when the armis displaced is arranged by means of microswitches oran optical system, to switch on a high resolution pulsecounter and a microsecond timer.

The drain valve is closed, and when the level reachesthe preset value, the balance arm starts thecounting procedure.

The operator now re-sets the balance arm, andattaches weights equal to the desired calibrationvolume whilst the collecting tank is filling.

When the second level is reached, the balance armagain deflects and closes the gating circuit of thecounters.

Thus for one given flowrate, we can calculate pulsesper unit of volume, and also the exact flowrate atwhich the calibration took place. This procedure is

then repeated at ten points over the operating rangeof the meter. Readings of pressure loss and outputvoltage are taken and the a.c. waveform is examinedon an oscilloscope to detect any abnormalities in therotor blades etc.

A full 10 point calibration certificate is supplied withevery flowmeter.


nixon flowmeters industrial type turbine

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